A strabismus or 'squint' is when your eyes don't line up correctly. Normally, people's eyes look in the same direction at the same time, moving in sync with each other. But if you have a squint, one eye (or both) moves in a different direction. If it's not treated, it can really affect your vision.
To understand why people squint, it's useful to know about six eye muscles.
Have you been told that you or your child might have a squint? This can be concerning, but it could also help explain visual problems you've noticed.
Strabismus happens when there's a problem with one or both of your eyes. It means they don't line up with each other when trying to focus on something. This can make it harder to see things as clearly. Squints usually start in childhood, but you can get adult strabismus too.
Many people mistake squint for 'lazy eye' (amblyopia). While they have some similarities ‑ and strabismus can lead to lazy eye ‑ they are different conditions, with different treatments.
Squints are usually present at birth or begin in the first six months of childhood. They are often related to vision problems like myopia (short‑sightedness) or astigmatism. Strabismus develops because the eye is trying to overcome this problem. There are other causes of childhood squint too (see below).
Having crossed eyes is fairly common among newborns, and not necessarily something to worry about. But if the squint keeps happening after about three months, speak with your child's GP or take them for an eye test at the optometrist.
Some people develop squints later in life. They're often related to health problems such as diabetes, stroke or eye injuries. Other times, an adult has simply had their squint since childhood.
Many people mistake strabismus for 'lazy eye' (amblyopia). While they have some similarities, they are different conditions, with different causes and treatments.
There are several types of squints, based on which way the eye with the squint is looking. Exotropia (eye looking outwards) and esotropia (eye looking inwards) are the most common. Here you can see how a few different types of squint might look.
Squint or strabismus – misaligned eye muscles
Exotropia – when the eye is directed outwards
Esotropia – when the eye is directed inwards
Hypertropia – when the eye is directed upwards
Hypotropia – when the eye is directed downwards
Cyclotropia – when the eye has rotated / torsion
Example of three types of Strabismus
The most obvious symptom of a squint is that the person's eyes don't line up. It might happen all the time, or it might come and go. However, squints can be subtle and it's not always possible to tell just by looking.
Squint symptoms are similar in children and adults. The big difference is that adults may be more aware of the change in their vision. Unlike very young children, they can also describe their symptoms more easily. Here are some of the main symptoms of strabismus.
One or both eyes may turn inwards (esotropia), outwards (exotropia), upwards (hypertropia), downwards (hypotropia) or rotated (cyclotropia).
People with strabismus may tilt or twist their heads to help adjust their vision when trying to focus.
People with a squint often experience double vision, blurred vision or difficulties perceiving depth. Younger children or babies may not be able to explain what's happening, but an optometrist can help.
Some people who have strabismus find they get a feeling of pulling, tugging or weakness around their eyes.
People who have a squint often try to adjust for visual problems by closing the affected eye.
Book an eye testIt's not always clear why an individual has developed a squint. Some people are born with them, while others develop them later in life. These are the most common causes of strabismus in children and adults.
Children and babies often develop squints because they're trying to overcome a vision problem. If a child has short‑sightedness or astigmatism one eye might turn to try and help focus on a blurry image.
Illnesses such as measles, meningitis or other viral infections can lead to children developing squints.
Weakness of the child's eye muscles may be the cause of their strabismus.
Children with genetic conditions such as Down syndrome and Noonan syndrome are more likely to have strabismus.
Strabismus sometimes runs in families. One study found that just over 30% of people with a squint have a close relative who also has strabismus.
Children with conditions like cerebral palsy or hydrocephalus may be more likely to have a squint.
People sometimes develop strabismus after an injury to the eye or head which damages eye muscles or nerves.
A stroke can affect the muscles and nerves around the eye, causing a squint. Studies have found that that over 16% of stroke survivors go on to develop a squint.
Some other medical conditions can cause adult strabismus, including Graves' disease, neurological conditions and diabetes.
Learn more about diabetic retinopathy
Having a squint can be challenging, especially for children. It might affect how they're treated by their peers and make it harder to see things clearly in school. This can lead to frustration or learning difficulties. Squint treatments are often very effective, particularly when started early. If you’re concerned about your child’s eyes, booking a test with an optometrist is a helpful first step.
A strabismus or squint can be diagnosed with a comprehensive eye exam. At Specsavers, our optometrists use a few different techniques to diagnose strabismus.
The optometrist will ask about your squint symptoms, and any family history of strabismus. They may also ask about related symptoms, such as headaches or double vision.
Your optometrist will inspect the eye to see if there is a noticeable squint or any other irregularities.
You or your child will wear special glasses so the optometrist can check eye alignment. Depending on where you are in the world, they may use tests like the Krimsky or prism bar cover test.
People with strabismus can struggle with depth (how far away 3D objects are). There are several stereoacuity tests where you will be asked to look at images or dots and say what you can see.
You or your child will focus on an object while one eye is covered. The optometrist checks how the uncovered eye moves to spot signs of a squint.
In this exam, you look directly at a point of light. If your eyes are lined up correctly, the light should bounce straight back, but if they're not lined up, the light will reflect away.
Your distance and near vision are checked using a Snellen chart. The optometrist places different lenses in front of your eyes to find the right prescription.
Book an eye testIf you or your child have been diagnosed with strabismus, the optometrist will create a treatment plan. At Specsavers, our optometrists have a lot of experience helping to treat people with squints in New Zealand.
There are a few different kinds of treatment available, depending on the underlying causes of the squint.
It's really important to get strabismus treated by an optometrist, because it won't go away on its own and there aren't any 'home remedies' that can resolve it. Left untreated, it can get worse and lead to long term vision problems. Here are some common treatments for strabismus.
Glasses can help to correct a squint if it is caused by a problem with your eyesight. Using strabismus glasses means your eyes don't need to work so hard to focus, allowing the eye muscles to start working in sync. The optometrist might also prescribe special prism glasses that are designed in a way that bends light for the eye with the squint, which can help with seeing things more clearly.
Exercises like pencil pushups (bringing a pencil slowly towards your nose) or near‑far focus shifting can help improve eye coordination and muscle control in people with strabismus.
For some people, it can be helpful to give injections into certain eye muscles which can weaken them. This can then help the eyes line up better.
Strabismus surgery may be an option if other treatments aren’t helping with your squint. The surgery involves moving the muscles that control the eye so that they line up as they're meant to.
This treatment method is recommended for lazy eye, however wearing an eye patch will not help to correct the alignment of the eyes and strabismus.
Book an eye testSquint treatments are usually highly effective, so the outlook for childhood squints is usually very good.
If the squint is diagnosed early and the child gets treated fast, the child will normally go on to have good vision for the long term. However, the longer a squint goes untreated, the harder it can be to resolve.
This is why it's so important to get children's eyes checked early. If you notice any symptoms of a squint in a child older than three months, speak with their GP or book an appointment with an optometrist.
Squint and strabismus mean the same thing ‑ when a person's eyes don't line up. 'Strabismus' is the medical term, and it's more often used by optometrists and other medical professionals. 'Squint' is the non‑medical term for this issue. Whichever words you use, our optometrists will understand what you mean.
For most people, strabismus surgery is very quick ‑ usually it lasts less than one hour. You will be put under general anaesthetic and will be asleep. Most people who have strabismus surgery can go home the same day.
No, squints don't go away on their own. If a squint is left untreated, it may get worse and can cause long term sight problems. This is why it's so important to get a squint seen by a doctor or optometrist as soon as possible.
Strabismus surgery is low risk and is normally successful. But like any surgery, things can go wrong. Risks include infection, under‑ or over‑correction of the squint, scarring, allergic reaction to anaesthetic or, very rarely, loss of vision. Ask your doctor or surgeon if you have any doubts.
No, it's rarely too late to do something about strabismus. Even if you, or a child you care for, have had strabismus for many years, there are still treatments that can help. It is generally better to get strabismus treated as early as possible, and treatments may be less effective the older the person is. But glasses, exercises, injections or even surgery can improve vision for people who've had a squint for many years.
Yes, every year many adults in New Zealand develop squints. Some of the main causes include strokes, head injuries, and certain diseases such as diabetes. Speak with your GP or optometrist about possible treatments.
If a squint doesn't get treated, it can get worse over time and lead to long‑term sight problems. The person's brain may start ignoring signals from the affected eye, meaning their vision gets worse.
You might be able to drive if you have a squint, but it depends on your symptoms, if it's being treated, and how significant your sight problems are. According to the NZTA, people with eyesight problems will need to pass an eyesight screening test before they can apply for a licence.
AA Members are entitled to a free eye test (valued at $60), once every two years. Remember to present your AA Membership card in‑store.
Cleveland Clinic (2023) Strabismus (Eye Misalignment) Available at: https://my.clevelandclinic.org/health/diseases/strabismus‑eye‑misalignment
Rowe, F. (2009) The profile of strabismus in stroke survivors Available at: https://pubmed.ncbi.nlm.nih.gov/19521433/
Sanchez, M., and Whitman, M. (2023) Genetics of strabismus Available at: https://www.frontiersin.org/journals/ophthalmology/articles/10.3389/fopht.2023.1233866/full
If your vision looks misty or washed out, especially in bright light or when driving at night, it could be cataracts.
When your cornea is shaped more like a rugby ball than a soccer ball, it can cause astigmatism, leading to blurred or distorted vision.
Long‑sightedness can cause blurry near vision even if your distance vision is fine.
Short‑sightedness (myopia) affects distance vision, but usually doesn’t impact close‑up tasks.
Glaucoma can develop gradually and cause vision loss if not caught early, often affecting side vision first.
Diabetes can affect the blood vessels at the back of your eye, leading to diabetic retinopathy and vision problems.
If your sight seems foggy or blurred, it could be caused by cataracts or another condition affecting your eye health.
Double vision means seeing two images of a single object, which can happen when the eyes are not aligned or working together properly
Do your eyes feel tried, sore or gritty? Dry eye could be the culprit, making vision cloudy, or as if you have glazed eyes.
This is when the edges of your eyelids get inflamed due to an infection or skin problem. It can also make the whites of your eyes appear pink or red.
Learn more about blepharitis
Seeing specks, spots or sudden flashes of light? These are common – but can also be a sign of a serious eye condition. It is worth checking out if they’re new or getting worse.
A chalazion is a blocked oil gland in the eyelid that causes a firm, usually painless lump and can lead to eyelid swelling or blurred vision.
Eye tests play a huge part in making sure your eyes stay healthy.
Check your vision
At Specsavers we are focused on caring for your eyes and giving you the best possible vision.
What to expect in‑store
An eye test is not just about getting glasses – it is a vital health check for your eyes.
All about eye testsFree exam for AA Members applies to standard eye examinations only, normally valued at $60. Excludes contact lens examination and visual field checks. Limited to one per AA Member every two years. Available to current AA Members upon presentation of AA Membership card.
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